CN1437773A - Multilayer structures as stable hole-injecting electrodes for use in high efficiency organic electronic device - Google Patents

Abstract

The present invention describes a multilayer anode structure (104) for an electronic device (100) such as a polymer light emitting diode. The multilayer anode includes a high conductivity organic layer (114) adjacent to the photoactive layer (102) and a low conductivity layer (112) between the high conductivity organic layer and the anode's electrical connection layer (110). ). The anode structure enables the polymer light-emitting diode to have high brightness, high efficiency and long working life. The resistivity of the multilayer anode structure of the present invention is high enough to avoid crosstalk in passively addressed pixelated polymer light emitting displays; the multilayer anode structure of the present invention also enables long lifetime of the pixelated polymer light emitting displays.

Description

Multilayer structures as stable hole-injecting electrodes for high-efficiency organic electronic devices

field of invention

The present invention relates to organic electronic devices. More specifically, it relates to multilayer hole-injecting electrodes (anodes) for electronic devices.

Description of prior art

Organic electronic devices, such as light-emitting diodes, photodetectors, and photovoltaic cells, can be formed from a thin layer of electroactive organic material sandwiched between two electrical contact layers. Electroactive organic materials are organic materials that exhibit electroluminescence, photosensitivity, charge (hole or electron) transport and/or injection, electrical conductivity and/or exciton blocking. This material can be a semiconductor. At least one of the electrical contact layers is transparent to light so that light can pass through the electrical contact layer to or from the layer of electroactive organic material. Other devices with similar structures include photoconductors, photoresist cells, photodiodes, photoswitches, transistors, capacitors, resistors, chemi-resistive sensors (gas/vapor sensitive electronic probes, chemical and biological sensors), write-in sensors and electrochromic devices (smart windows).

Light-emitting diodes (LEDs) with conjugated organic polymer layers as light-emitting elements have attracted attention for their potential use in display technology [J.H. Burroughs, D.D.C. Bradley, A.R. Brown, R.N. Marks, K. Mackay, R.H. Friend , P.L. Burns and A.B. Holmes, Nature 347, 539 (1990); D. Braun and A.J. Heeger, Appl. Phys. Lett., 58, 1982 (1991)]. Patents related to polymer LEDs include the following: R.H. Friend, J.H. Burroughs and D.D. Bradley, US Patent 5,247,190; J. Heeger and D. Braun, US Patents 5,408,109 and 5,869,350. The above references and all other articles, patents, patent applications, etc. cited herein are hereby incorporated by reference.

In the most basic form of these diodes, a layer of a conjugated organic polymer is used with a hole-injecting electrode (anode) bonded to one side and an electron-injecting electrode (cathode) bonded to the other, with There is a transparency to the light generated when the conjugated polymer layer is subjected to a voltage.

In many applications, especially in displays, arrays of such diodes are integrated. In these applications, there is generally a unit body of the active polymer, and the electrodes are patterned so that the array has the desired number of pixels. With active polymer monomer-based arrays and patterned electrodes, there is a need to minimize interference or "cross talk" between adjacent pixels. This need has been addressed by changing the nature of the contact between the active polymer body and the electrodes.

The desire to increase operating life and efficiency and the desire to minimize "crosstalk" often seem to be at odds. Utilizing high conductivity contacts to the active material promotes high efficiency and long operating life. When the resistance between adjacent pixels is high, the "crosstalk" can be suppressed to a minimum. A structure that favors high conductivity and thus high efficiency and long operating life is precisely at odds with the conditions preferred for low "crosstalk".

According to US Patent No. 5,723,873, placing a layer of conductive polyaniline (PANI) between the hole-injecting electrode and the active material is beneficial to improve the efficiency of the diode and reduce the turn-on voltage of the diode.

Hole-injecting anodes, including conductive polyaniline, can provide sufficiently high resistance to avoid the disadvantage of "crosstalk" in pixelated polymer light-emitting displays. But the lifetime of such high-resistance polyaniline devices is not long enough for many industrial applications. Furthermore, devices fabricated with anodes containing polyaniline layers require high operating voltages.

Further developments by C. Zhang, G. Yu, and Y. Cao [US Patent 5,798,170] using a layer of polyaniline or a blend containing polyaniline between the ITO and light-emitting polymer layers demonstrated long operating lifetimes for polymer LEDs.

Despite the advantages of polymer LEDs described in US Pat. No. 5,798,170, the typically low electrical resistance of polyaniline prevents polyaniline from being used in pixelated displays. For use in pixelated displays, the polyaniline layer should have a high sheet resistance, otherwise the lateral conductance will cause crosstalk between adjacent pixels. The resulting leakage between pixels can greatly impair efficacy and limit the resolution and clarity of the display.

It is not a good choice to increase the sheet resistance of polyaniline by reducing the film thickness, because the thinner film reduces the manufacturing yield due to the formation of electrical shorts. This is clearly shown in Figure 1, which shows the fraction of "leakage" pixels in a 96x64 array as a function of the polyaniline blend layer thickness. Therefore, to avoid short circuits, it is necessary to use a thicker polyaniline layer with a thickness of ~200 nm.

In polymer light-emitting displays, good operating lifetime and low operating voltage have been achieved by using a layer of polyethylenedioxythiophene (PEDT) between the indium/tin oxide (ITO) anode layer and the light-emitting polymer layer. And realized. PEDT, as commonly manufactured, inherently has low resistivity. However, for use in pixelated displays, the PEDT layer needs to have a high sheet resistance, otherwise the lateral conductance would cause crosstalk between adjacent pixels, and the resulting leakage between pixels would greatly impair efficacy and limit the display. resolution and clarity.

Therefore, there is currently a need for an anode structure in a light emitting device meeting the requirements of industrial applications, which can avoid crosstalk between pixels and has a low operating voltage and a longer operating life.

Summary of the invention

The present invention generally relates to a multilayer anode structure suitable for use in organic electronic devices such as diodes and pixelated displays.

The multilayer anode comprises a first layer, a second layer in contact with the first layer and a third layer in contact with the second layer, the first layer comprising a layer of high electrical conductivity having the electrical conductivity of the first layer high rate contact layer, the second layer comprising a conductive organic material having a second layer conductivity, the third layer comprising a conductive organic polymer having a third layer conductivity, the third layer having a high conductivity The conductivity of the second layer is lower than that of the first layer.

The multilayer structure provides high enough electrical resistance to avoid crosstalk in passively addressed pixelated polymer light emitting displays; the multilayer anode structure of the present invention also provides the desired resistance for pixelated polymer light emitting displays in industrial applications. The required low working voltage and long working life.

The present invention also provides an improved configuration for electronic devices such as pixelated polymer light emitting displays. This configuration also results in a highly efficient, long operating lifetime PED while avoiding excessive crosstalk. The present invention generally relates to the use of multilayer anode structures in such devices. Thus, in one aspect, the present invention provides an improved polymer light emitting diode. The improved diode is made from a layer of an active light-emitting polymer whose first side is in contact with the cathode and whose second side is in contact with the transparent anode. The improvement includes a multilayer transparent anode itself made of a high conductivity transparent first contact layer, a transparent second layer in contact with the first contact layer, and a third layer in contact with the second layer and the active light-emitting polymer layer. three floors. The second layer contains a conjugated conductive organic polymer blend and has high electrical resistance. The third layer is thin and contains a conductive organic polymer that has a lower electrical resistance than the material of the second layer.

Although the multilayer electrodes of the present invention are suitable for use in both non-pixelated and pixelated electronic devices, using such improved multilayer electrode structures, when many diodes are arranged in an array such as occurs in pixelated light-emitting displays This is particularly advantageous because the anode structure minimizes the level of crosstalk while allowing longer and higher efficiencies than previously described arrays.

In this aspect, the present invention provides an improved array of polymer light emitting diodes. This improved diode array is made of an active light emitting polymer layer with a first face contacting a patterned cathode and a second face contacting a patterned transparent anode, the patterning of the anode and cathode determining the array of light emitting diodes, said modification comprising A multilayer transparent anode comprising a first layer comprising a patterned high-conductivity transparent contact layer, a non-patterned second layer in contact with said first layer, and a layer in contact with the second layer and A non-patterned third layer in contact with the active light-emitting polymer layer, the second layer comprising a conjugated conductive organic polymer blend and having higher resistance (lower conductivity), the third layer Contains a conductive organic polymer and has lower resistance (higher conductivity) than the second layer.

As used herein, the term "organic electroactive material" refers to any organic material that exhibits specific electroactivity, such as electroluminescence, photosensitivity, charge transport and/or charge injection, electrical conductivity, and exciton blocking, among others. The term "solution-processed organic electroactive material" refers to any organic electroactive material to which a suitable solvent has been added during the formation of layers in electronic device integration. The term "charge", when used to refer to charge injection/transport, refers to either or both hole and electron transport/injection, depending on the context. The term "photoactive" organic material refers to any organic material that exhibits electrical activity such as electroluminescence and/or photosensitivity. The terms "conductivity" and "bulk conductivity" are used interchangeably, with values expressed in units of Siemens per centimeter (S/cm). Furthermore, the terms "surface resistivity" and "sheet resistance" are used interchangeably to refer to the resistance value for a given material as a function of sheet thickness, with values expressed in units of Ω/sq. Likewise, the terms "volume resistivity" and "resistivity" are used interchangeably to refer to electrical resistivity, which is a fundamental property (i.e., invariant to size) of a particular material and is measured in ohm-centimeters (Ω- cm) as a unit. Resistivity is the inverse of conductivity.

Brief description of the drawings

The invention will be described with reference to the accompanying drawings. In these drawings,

Figure 1 is a background art reference graph showing the fraction of "leakage" pixels (in a 96x64 array) versus the thickness of the polyaniline layer.

Figure 2A is a cross-sectional view, not to scale, of a pixel in an organic electronic device comprising a photoactive layer of the present invention.

Figure 2B is an enlarged cross-section of the pixel shown in Figure 2A, highlighting the multilayer anode structure.

Fig. 2C is a schematic structural view of a passive addressable pixelated organic electronic device containing a photoactive layer according to the present invention.

Figure 3 is a graph illustrating the stress-induced degradation of three devices at 70 °C, one device has a polyaniline (emeraldine-salt) layer (PANI(ES)), and one device has a layer composed of polyaniline and polyacrylamide (PANI(ES)-PAM), and one device had a layer of poly(ethylenedioxythiophene) (PEDT). The solid line represents the operating voltage, and the dashed line represents the light output.

Figure 4 is a graph illustrating the stress-induced degradation at 70°C of devices containing PANI(ES)-PAM/PEDT bilayers with different thicknesses of PEDT. The solid line represents the operating voltage, and the dashed line represents the light output.

Figure 5 is a graph illustrating the stress-induced degradation at 80°C of a series of devices containing PANI(ES)-PAM/PEDT bilayers of different PANI(ES)-PAM blends. The solid line represents the operating voltage, and the dashed line represents the light output.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As best shown in FIGS. 2A , 2B and 2C, the electronic device 100 of the present invention comprises a photoactive layer 102 between a cathode 106 and a multilayer anode 104 . Anode 104 includes a conductive first layer 110 having a first layer conductivity, a low conductivity second layer 112 having a second layer conductivity and a high conductivity third layer having a third layer conductivity 114. The electrical conductivity of the third layer is greater than that of the second layer but lower than that of the first layer. Anode 104 and the entire diode structure may be carried on substrate 108 .

The organic polymer based diode 100 uses an anode with a higher work function; A ^material with a lower work function is preferred for the cathode 106; The holes injected at the anode and the electrons injected at the cathode recombine radiatively in the active layer to emit light. Criteria for electrodes suitable for this field have been detailed by ID Parker in J. Appl. Phys, 75, 1656 (1994). Device configuration

As best seen in Figure 2C, each pixel in an organic electronic device 100 includes an electron injection (cathode) contact 106 which acts as an electrode in front of a photoactive organic material 102 deposited on a multilayer anode 104 of the present invention , functioning as a second (transparent) electron-withdrawing (anode) electrode. The multilayer anode (consisting of layers 110 , 112 and 114 ) is deposited on a substrate 108 partially coated with a first layer 110 . A low conductivity second layer 112 and a high conductivity third layer 114 are deposited over the first layer 110 . Cathode 106 is electrically connected to contact pad 80 and anode 110 is electrically connected to contact pad 82 . Layers 102 , 106 , 108 , 110 and 112 are then sealed from the environment by a sealing layer 114 . When the electronic device is a light emitting device, light is emitted from the device in the direction indicated by arrow 90 when electricity is applied through contact pads 80 and 82 outside of seal 70 . When the electronic device is a photodetector, light is received by the device in the direction opposite to arrow 90 (not shown).

The description of the preferred embodiment is organized by these various components. More specifically, it contains the following sections:

Photoactive layer(102)

Multilayer Anode(104)

Conductive first layer(110)

  Low conductivity second layer (112)

  High conductivity third layer(114)

Cathode(106)

Substrate(108)

Contact gasket (80, 90)

optional layer

Manufacturing Technology Photoactive Layer(102)

Depending on the application of the electronic device, the photoactive layer 102 may be a light-emitting layer that is activated by the application of a voltage (for example, in a light-emitting diode or a light-emitting electrochemical cell), i.e., a layer that responds to radiation whether or not a bias voltage is applied. A material that responds to energy and produces a signal (such as in a photodetector). Examples of photodetectors include photoconductors, photoresistors, photoswitches, phototransistors, photocells, and photovoltaic cells, as these terms are described in Markus, John, Electronics and Nucleonics Dictionary, 470 and 476 (McGraw-Hill, Inc. 1966) have been described.

When the electronic device is a light emitting device, the photoactive layer 102 will emit light when a sufficient bias voltage is applied to the electrical contact layer. Suitable active light-emitting materials include organic molecular materials such as anthracene, butadiene, coumarin derivatives, acridine and stilbene derivatives, see, for example, U.S. Patent 4,356,429 to Tang, U.S. Patent 4,539,507 to Van Slyke et al., relevant parts thereof Included here for reference. Alternatively, such materials may also be polymeric materials, such as those described by Friend et al. (U.S. Patent 5,247,190), Heeger et al. (U.S. Patent 5,408,109), Nakano et al. (U.S. Patent 5,317,169), the relevant portions of which are incorporated herein by reference . The luminescent material may be dispersed in a matrix of another material, with or without additives, but preferably forms a single layer. In a preferred embodiment, the electroluminescent polymer comprises at least one conjugated polymer or copolymer comprising segments of π-conjugated moieties. Conjugated polymers are well known in the art (see "Conjugated Polymers", edited by J.-L. Bredas and R. Silbey, Kluwer Academic Press, Dordrecht, 1991). Typical material types include, but are not limited to, the following:

(i) poly(p-phenylene vinylene) and derivatives thereof substituted at various positions on the phenylene moiety;

(ii) poly(p-phenylene vinylene) and its derivatives substituted at different positions of the vinylene moiety;

(iii) Poly(arylenevinylene), where the arylene group can be a moiety such as naphthalene, anthracene, furylene, thienylene, oxadiazole, or have functional substituents at various positions one of such parts of the

(iv) derivatives of polyarylenevinylene, wherein the arylene group may be substituted at different positions of the arylene moiety as in (iii) above;

(v) derivatives of polyarylene vinylene, wherein the arylene group may be substituted at different positions of the vinylene moiety as in (iii) above;

(vi) Copolymers of arylene vinylidene oligomers and non-conjugated oligomers and derivatives of such polymers substituted at different positions of the arylene moiety, such polymers in the vinylene moiety Derivatives substituted at different positions and derivatives of such polymers substituted at different positions on the arylene and vinylidene moieties;

(vii) Polyparaphenylene and its derivatives substituted at different positions of the phenylene moiety, including ladder polymer derivatives such as poly(9,9-dialkylfluorene);

(viii) polyarylenes and their derivatives substituted at different positions of the arylene moiety;

(ix) Copolymers of oligomeric arylenes and non-conjugated oligomers, and derivatives of such polymers substituted at different positions of the arylene moiety;

(x) polyquinoline and its derivatives;

(xi) Copolymers of polyquinoline with p-phenylene and soluble functional moieties;

(xii) Rigid rod polymers such as poly(p-phenylene-2,6-benzobithiazole), poly(p-phenylene-2,6-benzobisoxazole), poly(p-phenylene Phenyl-2,6-benzimidazole) and their derivatives.

More specifically, active materials may include, but are not limited to, poly(phenylene vinylene) PPV and alkoxy derivatives of PPV, for example, poly(2-methoxy-5-(2'-ethyl -hexyloxy)-p-phenylenevinylene) or "MEH-PPV" (US Patent 5,189,136). BCHA-PPV is also an attractive active material. (C. Zhang et al., J. Electron. Mater., 22, 413 (1993)). PPPV is also applicable. (C. Zhang et al., Synth. Met., 62, 35 (1994) and references therein) luminescent conjugated polymers soluble in common organic solvents are preferred because they enable relatively simple fabrication of devices [A. Heeger and D. Braun, US Patents 5,408,109 and 5,869,350].

More preferred active light-emitting polymers and copolymers are the soluble PPV materials described by H. Becker et al. in Adv. Mater. 12, 42 (2000), referred to herein as C-PPV. Blends of such polymers with other semiconducting polymers and copolymers that will electroluminescence may also be used. When the electronic device 100 is a photodetector, the photoactive layer 102 responds to irradiating energy and generates a signal when biased or unbiased. Materials that respond to irradiated energy and produce a signal when biased (as in the case of photoconductors, photoresistors, photoswitches, phototransistors, and photodiodes) include, for example, many conjugated polymers and electroluminescent materials. Materials that respond to irradiated energy and produce a signal when not biased (eg in the case of photoconductors, photovoltaic cells) include materials that chemically react with light and thereby produce a signal. Such chemically photosensitive reactive materials include, for example, many conjugated polymers and electro- and photo-luminescent materials. Specific examples include, but are not limited to, MEH-PPV ("Optocouplers made of semiconducting polymers", G.Yu, K.Pakbaz, and A.J.Heeger, Journal of Electronic Materials, Vol.23, pages 925-928 (1994 ); and MEH-PPV composites with CN-PPV ("High Efficiency Photodiodes Fabricated from Interpenetrating Polymer Networks", J.J.M. Ha11s et al. (Cambridge Group), Nature, Vol.376, pp. 498-500, 1995). Electroactive organic materials can be tailored to emit light at different wavelengths.

In certain embodiments, the polymeric photoactive material or the organic molecular photoactive material is present in the photoactive mixture as a mixture of carrier organic materials (polymers or organic molecules) from 0% to 75% by weight, based on the total weight of the mixture. In the active layer 102. The criteria for selecting the carrier organic material are as follows: the material should form mechanically cohesive films at low concentrations and be stable in solvents that disperse or dissolve the film-forming conjugated polymer. To minimize processing difficulties, ie, excessive viscosity or uniformity of formation, low concentrations of carrier material are preferred; however, the carrier concentration should be high enough to allow cohesive structures to form. When the carrier is a polymeric material, preferably the carrier polymer is a high molecular weight (M.W > 100,000) flexible chain polymer, for example, polyethylene, isotactic polypropylene, polyethylene oxide, polystyrene, and the like. Such macromolecular materials are capable of forming cohesive structures from a wide variety of liquids, including water, acids, and many polar or nonpolar organic solvents, under suitable conditions readily determined by those skilled in the art. Films or sheets made of such carrier polymers have sufficient mechanical strength when the polymer concentration is as low as 1% by volume, or even as low as 0.1% by volume, so that coating and subsequent processing can be performed as required. Examples of such cohesive structures are those composed of polyvinyl alcohol, polyethylene oxide, polypara-(terephthalate), polyparabenzamide, and the like, and other suitable polymers. On the other hand, if blending of the final polymer cannot be performed in a polar environment, a non-polar support structure is chosen, for example, those containing polyethylene, polypropylene, polybutadiene, etc.

The typical film thickness of the photoactive layer ranges from hundreds of angstroms (200 Å) to thousands of angstroms (10,000 Å) (1 Å=10 ^-8 cm). Although active film thickness is not critical, device performance can generally be improved by using thinner films. The preferred thickness is from 300 Å to 5,000 Å. Multilayer Anode(104)

The multilayer anode (104) includes a conductive first layer (110), a low conductivity second layer (112), and a high conductivity third layer (114).

The thickness of each layer 110, 112, and 114 depends on the desired transparency and resistivity of those layers, which in turn depend on the composition of the layers.

In a device of the invention comprising a photoactive layer, one electrode is transparent to allow light to be emitted from the device or received by the device. More generally, the anode is a transparent electrode, although the invention can also be used in embodiments where the cathode is a transparent electrode.

As used herein, the term "transparent" is defined as "transmitting at least about 25%, preferably at least about 50%, of the amount of light of a particular wavelength of interest". So even though a material's ability to transmit light varies with wavelength, it is still considered transparent if it does meet the 25% or 50% criterion at the given wavelength of interest. As known to those working in the field of thin films, metals can achieve considerable transparency if the layers are very thin, for example in the case of silver and gold, the thickness is less than about 300 Å, especially about 20 Å to about 250 Å, silver has a relatively Colorless (uniform) transmission, gold tends to transmit yellow to red wavelengths. Similarly, for materials such as ITO, PANI and PEDT, the layer thickness can reach transparency in the range of 100 Å-10,000 Å.

In addition to the desired transparency, the composition of the layers in the multilayer anode 104 should be selected such that the conductivity of the third layer is less than that of the first layer and greater than that of the second layer. Thus, the choice of material for each layer in a multilayer anode depends on the composition of the other layers in the anode and the corresponding electrical conductivities of these other layers. Other factors determining the composition are described in the following sections dealing with specific layers. Conductive first layer(110)

The conductive first layer has a low resistance: preferably below 300Ω/sq, more preferably below 100Ω/sq.

The conductive first layer (110) of the composite anode (104) provides electrical contact to an external power source (not shown) and is a conductive layer made of a high work function material, very typically a work function Inorganic materials above about 4.5eV. Preferably, the conductive first layer 110 is composed of a material containing metal, mixed metal, alloy, metal oxide or mixed-metal oxide. Suitable metals include Group 11 metals, Groups 4, 5 and 6 metals and Groups 8-10 transition metals. If the anode 104 is to be light transmissive, a mixed metal oxide in Groups 12, 13 and 14, such as indium-tin-oxide, is typically used. The IUPAC numbering system is used throughout, wherein groups in the periodic table are numbered from 1 to 18 from left to right (CRC Handbook of Chemistry and Physics, 81st Edition, 2000). The first layer 110 may also comprise an organic material such as polyaniline as described in "Flexible light-emitting diodes made from soluble conducting polymer", Nature Vol. 357, pages 477-479 (11 June 1992).

Typical inorganic materials that function as anodes include metals such as aluminum, silver, platinum, gold, palladium, tungsten, indium, copper, iron, nickel, zinc, lead, etc.; metal oxides such as lead oxide, tin oxide, indium/tin-oxide Graphite; doped inorganic semiconductors such as silicon, germanium, gallium arsenide, etc. When using metals such as aluminum, silver, platinum, gold, palladium, tungsten, indium, copper, iron, nickel, zinc, lead, etc., the anode layer should be thin enough to be translucent. Metal oxides such as indium/tin-oxide are generally at least translucent.

While the anode is transparent, conductive metal-metal oxide mixtures can in some cases be transparent at thicknesses up to 2500 Å. When transparency is desired, the metal-metal oxide (or dielectric) layer preferably has a thickness of from about 25 to about 1200 Å. Low Conductivity Second Layer(112)

The resistivity of the second layer 112 should be high enough to prevent crosstalk or leakage from the multilayer anode and provide sufficient hole injection/transport. Preferably the volume conductivity of the low conductivity second layer is from about 10 ⁻⁴ S/cm to 10 ⁻¹¹ S/cm. More preferably, the volume conductivity of the second layer is 10 ^-5 S/em - 10 ^-8 S/cm.

The second layer 112 may comprise polyaniline (PANI) or an equivalent conjugated conductive polymer such as polypyrrole or polythiophene, very commonly in a blend with one or more non-conductive polymers. Polyaniline is particularly useful. Very commonly, polyaniline exists in the form of emeraldine salt (ES). Useful conductive polyanilines include homopolymers and derivatives, often as blends with bulk polymers (also known as bulk polymers). Examples of PANI are those described in US Patent 5,232,631.

In another embodiment, the second layer may comprise a conductive material such as N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-diphenyl] -4,4′-diamine (TPD) and bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane (MPMP), and the hole Injection/transport polymers such as polyvinylcarbazole (PVK), (phenylmethyl)polysilane, poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI); electronics and Hole injection/transport materials, such as 4,4'-N,N'-dicarbazole biphenyl (BCP); or light-emitting materials with good electron and hole transport properties, such as chelated oxidized compounds, For example tris(8-hydroxyquinato)aluminum (Alq ₃ ).

When the term "polyaniline" or PANI is used herein, it is generally taken to include substituted and unsubstituted materials, as well as other equivalent conjugated conductive polymers such as polypyrrole or polythiophene, for example polyethylenedioxythiophene ( "PEDT"), unless the context clearly indicates that only the specific unsubstituted form is being referred to. The term is also used in a manner that includes any accompanying dopants, especially acidic materials used to make polyaniline conductive.

In general, polyanilines are polymers and copolymers of molecular weight capable of forming films and fibers, derived from the polymerization of unsubstituted and substituted anilines of formula I:

其中，Formula I

in,

n is an integer of 0-4;

m is an integer from 1 to 5; provided that the sum of n and m is equal to 5; and

R is independently selected such that each occurrence of R is the same or different and is selected from the group consisting of: alkyl, alkenyl, alkoxy, cycloalkyl, cycloalkenyl, alkanol, alkyl Alkylthio, aryloxy, alkylthioalkyl, alkylaryl, arylalkyl, amino, alkylamino, dialkylamino, aryl, alkylsulfinyl, alkoxyalkyl , alkylsulfonyl, arylthio, arylsulfonyl, alkoxycarbonyl, arylsulfonyl, carboxylic acid, halogen, cyano or replaced by one or more sulfonic acid, carboxylic acid, halogen, nitro, Alkyl substituted with cyano or epoxy; or carboxylic acid, halogen, nitro, cyano, or sulfonic acid moiety; or any two R groups together can form a 3, 4, 5, 6 or 7 membered aromatic An alkylene or alkenylene chain of an aliphatic or aliphatic ring, which ring may optionally include one or more divalent nitrogen, sulfur or oxygen atoms. Without intending to limit the scope of the invention, the size of each R group is about 1 carbon atom (in the case of an alkyl group), via 2 or more carbon atoms up to about 20 carbon atoms, the total number of carbon atoms for n R from about 1 to about 40 carbon atoms.

Examples of polyanilines suitable for use in the practice of the invention are those of formula II-V:

Among them, n, m and R are as above, but since the hydrogen atoms are replaced by covalent bonds in the polymerization, m is minus 1 and the sum of n+m is equal to 4.

y is an integer equal to or greater than 0;

x is an integer equal to or greater than 1, provided that the sum of x and y is greater than 1; and

z is an integer equal to or greater than 1.

The substituted and unsubstituted anilines listed below are examples of anilines that can be used to prepare polyanilines suitable for use in the practice of this invention. Aniline 2,5-Dimethylaniline o-Toluidine 2,3-Dimethylaniline m-Toluidine 2,5-Dibutylaniline o-Ethylaniline Benzene-m-Dimethoxy 2, tetrahydronaphthylamine o-ethoxyaniline o-cyanoaniline m-butylaniline 2-thiomethylaniline m-hexylaniline 2,5-dichloroaniline m-octylaniline 3-(n-butane )aniline 4-bromoaniline 2-bromoaniline 3-bromoaniline 2,4-dimethoxyaniline 3-acetamidoaniline 4-mercaptoaniline 4-acetamidoaniline 4-methylthioaniline 5 -Chloro-2-methoxyaniline 3-Phenoxyaniline 5-Chloro-2-ethoxyaniline 4-Phenoxyaniline

Examples of suitable R groups are alkyl groups such as methyl, ethyl, octyl, nonyl, tert-butyl, neopentyl, isopropyl, sec-butyl, dodecyl, etc.; alkenyl groups such as 1 - propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 1-heptenyl, 1-octenyl, etc.; alkoxy such as propoxy, butoxy, methoxy , isopropoxy, pentyloxy, nonyloxy, ethoxy, octyloxy, etc.; cycloalkenyl, such as cyclohexenyl, cyclopentenyl, etc.; alkanol, such as butanol, pentanol , octanol; ethanol, propanol, etc.; alkylsulfinyl, alkylsulfonyl, alkylthio, arylsulfonyl, arylsulfinyl, etc., such as butylthio, neopentylthio Base, methylsulfinyl, benzylsulfinyl, phenylsulfinyl, propylthio, octylthio, nonylsulfonyl, octylsulfonyl, methylthio, isopropylthio , phenylsulfonyl, methylsulfonyl, nonylthio, phenylthio, ethylthio, benzylthio, phenyl (phenethyl)thio, naphthylthio, etc.; alkoxycarbonyl such as Methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, etc.; cycloalkyl such as cyclohexyl, cyclopentyl, cyclooctyl, cycloheptyl, etc.; alkoxyalkyl such as methoxymethyl, ethoxy ylmethyl, butoxymethyl, propoxyethyl, pentoxybutyl, etc.; aryloxyalkyl and aryloxyaryl, such as phenoxyphenyl, phenoxymethylene etc.; and various substituted alkyl and aryl groups such as 1-hydroxybutyl, 1-aminobutyl, 1-hydroxypropyl, 1-hydroxypentyl, 1-hydroxyoctyl, 1-hydroxyethyl, 2- Nitroethyl, trifluoromethyl, 3,4-epoxybutyl, cyanomethyl, 3-chloropropyl, 4-nitrophenyl, 3-cyanophenyl, etc.; Alkyl and aryl terminations and carboxylic acid terminations of alkyl and aryl groups such as ethylsulfonic acid, propylsulfonic acid, butylsulfonic acid, benzenesulfonic acid and the corresponding carboxylic acids.

Examples of R groups that are also suitable are divalent moieties formed from any 2 R groups, such as the formula

-(CH ₂ ) _n* -

wherein n ^* is an integer from about 3 to about 7, such as -(CH ₂ ) ₄ -, -(CH ₂ ) ₃ - and -(CH ₂ ) ₅ -, or optionally including heteroatoms such as oxygen and sulfur Moieties, such as -CH ₂ SCH ₂ - and -CH ₂ -O-CH ₂ -. Examples of suitable other R groups are divalent alkenylene chains comprising from 1 to about 3 conjugated double bond unsaturations, such as divalent 1,3-butadiene or the like moieties.

Preferred for use in the practice of the present invention are polyanilines of formulas II to V above, wherein:

n is an integer from 0 to about 2;

m is an integer of 2-4, the condition is that the sum of n and m is equal to 4;

R is an alkyl or alkoxy group of 1 to about 12 carbon atoms, cyano, halo or alkyl substituted with a carboxylic or sulfonic acid substituent.

x is an integer equal to or greater than 1;

y is an integer equal to or greater than 0; provided that the sum of x and y is greater than approximately 4, and

z is an integer equal to or greater than about 5.

In a more preferred embodiment of the invention the polyaniline is derived from unsubstituted aniline, ie n is 0 and m is 5 (monomer) or 4 (polymer). Generally, the number of monomeric repeat units is at least about 50.

As described in US Patent 5,232,631, polyaniline conducts electricity by the presence of an oxide or acid. In this role, acids are preferred, especially "functionalized protic acids". A "functionalized protic acid" is an acid whose counterion has preferably been functionalized to be compatible with the other components of the layer. As used herein, a "protic acid" is one that protonates polyaniline into a complex with said polyaniline.

In general, functionalized protic acids suitable for use in the present invention are those represented by formulas VI and VII:

A-R

or

         

in,

A is a sulfonic acid, selenic acid, phosphoric acid, boric acid or carboxylic acid group; or hydrogen sulfate, hydrogen selenate, hydrogen phosphate;

n is an integer of 1-5;

R is alkyl, alkenyl, alkoxy, alkanol, alkylthio, alkylthioalkyl; or alkaryl, aralkyl, alkyl containing 1 to about 20 carbon atoms Sulfinyl, alkoxyalkyl, alkylsulfonyl, alkoxycarbonyl, carboxylic acid, wherein the alkyl or alkoxy group contains 0 to about 20 carbon atoms; One or more sulfonic acid, carboxylic acid, halogen, nitro, cyano, diazo or epoxy substituted alkyl groups; or substituted or unsubstituted 3, 4, 5, 6 or 7 membered aromatic or alicyclic The carbocyclic ring may contain one or more heteroatoms such as nitrogen, sulfur, sulfinyl, sulfonyl or oxygen, such as thiophenyl, pyrrolyl, furyl, pyridyl.

In addition to the monomeric acid forms described above, R can also be a polymer backbone with a plurality of acid functional groups "A". Examples of polymeric acids include sulfonated polystyrene, sulfonated polyethylene, and the like. In these cases, the polymer backbone can be chosen to increase solubility in non-polar matrices or in more polar matrices where materials such as polymers, polyacrylic acid, or polyvinyl sulfonate can be used .

R' is the same or different in each occurrence and is alkyl, alkenyl, alkoxy, cycloalkyl, cycloalkenyl, alkanolyl, alkylthio, aryloxy, alkylthio alkylalkyl, alkylaryl, arylalkyl, alkylsulfinyl, alkoxyalkyl, alkylsulfonyl, aryl, arylthio, aryl suldmyl, alkoxycarbonyl, aryl Sulfonyl, carboxylic acid, halogen, cyano, or alkyl substituted by one or more sulfonic acid, carboxylic acid, halogen, nitro, cyano, diazo, or epoxy; or any 2 R substituents together It is an alkylene or alkenylene group that completes a 3, 4, 5, 6 or 7-membered aromatic or alicyclic carbocyclic ring or multiples thereof, such that one or more rings may include one or more nitrogen, sulfur , sulEmyl, sulfonyl or divalent heteroatoms such as oxygen. R' generally has about 1 to about 20 carbon atoms, especially 3 to 20, more especially about 8 to 20 carbon atoms.

Materials of formulas VI and VII above are preferred, wherein

A is sulfonic acid, phosphoric acid or carboxylic acid;

n is an integer of 1-3;

R is an alkyl, alkenyl, alkoxy group containing 6 to about 14 carbon atoms; or an aralkyl group with 4 to about 14 carbon atoms in an alkyl or alkyl moiety or alkoxy group; or 6- An alkyl group of about 14 carbon atoms substituted with one or more carboxylic acid, halogen, diazo or epoxy groups.

Each occurrence of R' is the same or different, and is alkyl, alkoxy, alkylsulfonyl or alkyl substituted by one or more halogen moieties containing 4-14 carbon atoms, and the alkyl moiety also has 4- 14 carbon atoms.

In a particularly preferred embodiment, very preferred for the practice of the present invention are the functionalized protonic acids of the formulas VI and VII above, wherein

A is sulfonic acid;

n is an integer of 1 or 2;

R is an alkyl or alkoxy group of 6 to about 14 carbon atoms; or an alkyl group of 6 to about 14 carbon atoms substituted with one or more halogens.

R' is an alkyl or alkoxy group containing 4-14 carbon atoms, especially 12 carbon atoms, or an alkyl group substituted by one or more halogens.

Preferred functionalized protic acids are organic sulfonic acids, such as dodecylbenzenesulfonic acid, more preferably poly(2-arylamido-2-methyl-1-propanesulfonic acid) ("PAAMPSA").

The amount of functionalized protic acid can vary depending on the desired conductivity. In general, a protic acid sufficiently functionalized is added to the polyaniline-containing mixture to form a conductive material. Usually the functionalized protic acid is used in an amount at least sufficient to obtain a conductive polymer (either in solution or solid form).

The polyaniline may be conveniently used in the practice of the present invention in any physical form. Examples of suitable forms are in Green, A.G., and Woodhead, A.E., J. Chem. Soc., 101, 1117 (1912) and Kobay.ashi et al., J. Electroanl. Chem., 177, 281-91 (1984) Those references are incorporated herein by reference. For unsubstituted polyaniline, useful forms include leuco emeraldine, protic emeraldine, emeraldine, nigrosine, and toluene-protic emeraldine forms, with emeraldine forms being preferred.

Pending PCT patent application PCT/US00/32545 by Cao, Y. and Zhang, C. discloses the formation of low conductivity blends of conjugated polymers and nonconductive polymers, and is incorporated herein by reference.

The particular bulk polymer(s) added to the conjugated polymer can vary. The choice of material can be based on the properties of the conducting polymer, the method used to blend the polymers and the method used to deposit the thin layer on the device.

Materials can be blended by dispersing one polymer in another, as a fine particle dispersion or as a solution of one polymer in another. Polymers are generally mixed in the liquid phase, and thin layers are generally laid down from the liquid phase.

We have had the best results with water soluble or water dispersible conjugated polymers and water soluble or water dispersible bulk polymers. In this case, the blend can be formed by dissolving or dispersing the two polymers in water and then casting the layer from the solution or dispersion.

Organic solvents can be used with organo-soluble or organodispersible conjugated polymers and bulk polymers. In addition, blends can be formed from the melt of the two polymers, or from a liquid prepolymer or the monomeric form of the bulk polymer, which is then allowed to polymerize or cure into the desired final material.

In cases where the presently preferred PANI is water soluble or water dispersible and it is desired to cast the PANI layer from an aqueous solution, the bulk polymer should be water soluble or water dispersible. In such cases, it is selected from, for example, polyarylamides (PAM), poly(acrylic acid), (PAA) poly(vinylpyrrolidone) (PVPd), acrylamide copolymers, cellulose derivatives, carboxyvinyl Polymers, Polyethylene Glycol, Polyethylene Oxide (PEO), Polyvinyl Alcohol (PVA), Polyvinyl Methyl Ether, Polyamine, Polyimine, Polyvinylpyridine, Polysaccharides and Polyurethane Dispersions.

Where casting of thin layers from non-aqueous solutions or non-aqueous dispersions is required, the bulk polymer may be selected from, for example, liquefiable polyethylene, isotactic polypropylene, polystyrene, polyvinyl alcohol, polyethylene vinyl Acetate, polybutadiene, polyisoprene, ethylene vinylidene copolymer, ethylene-propylene copolymer, polyethylene terephthalate, polybutylene terephthalate, and nylon, such as nylon 12. Nylon 8, nylon 6, nylon 6.6, etc., polyester materials, polyamides such as polyacrylamide, etc.

In those cases where one polymer is to be dispersed in another, common solubility of the individual polymers may not be required.

The relative proportions of polyaniline to bulk polymer or prepolymer can vary. From 0 to up to 20 parts by weight of bulk polymer or prepolymer can be formulated for each part of polyaniline so that there are 0.5 to 10 parts, especially 1 to 4 parts of bulk material for each part of PANI.

The solvent to be used to cast the thin layer is chosen to suit the properties of the polymer.

In a preferred system, both the PANI and the bulk polymer are water-soluble or water-dispersible, and the solvent system is an aqueous solvent system, such as water or water with one or more polar organic materials such as lower alcohols, ketones, and esters. Mixture of oxygenated hydrocarbons.

These materials include, but are not limited to, mixtures of water with methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, and the like.

If desired, but generally not preferred, solvent systems of polar organic liquids can be used.

Non-polar solvents are most commonly used in the case of conductive polymers such as PANI and bulk polymers that are insoluble or non-dispersible in water.

Examples of suitable common non-polar solvents include the following materials: substituted or unsubstituted aromatic hydrocarbons such as benzene, toluene, p-xylene, m-xylene, naphthalene, ethylbenzene, styrene, aniline, etc.; Alkanes, such as pentane, hexane, heptane, octane, nonane, decane, etc.; cycloalkanes, such as decalin; halogenated alkanes, such as chloroform, bromoform, methylene chloride, etc.; halogenated aromatics, such as chlorinated Benzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, etc.; higher alcohols such as 2-butanol, 1-butanol, hexanol, pentanol, decanol, 2-methyl- 1-propanol, etc.; higher ketones such as hexanone, butanone, pentanone, etc.; heterocycles such as morpholine; perfluorohydrocarbons such as perfluorodecalin, perfluorobenzene, etc.

The thickness of the second layer 112 will be selected according to the performance of the diode. In the case where the composite anode is to be transparent, it is generally preferred that the PANI layer is as thin as practically possible, taking into account the failure problem shown in Figure 1 . Typical thicknesses range from about 100 Å to about 5000 Å. When transparency is required, the thickness is preferably about 100 Å to about 3000 Å, especially about 2000 Å.

When the second layer 112 comprises a PANI(ES) blend and has a film thickness of 200 nm or more, the resistivity of the second layer should be greater than or equal to 10 ⁴ Ω-cm to avoid crosstalk and inter-pixel leakage. Values greater than 10 ⁵ Ω-cm are preferred. Even at 10 ⁵ Ω-cm, there is still some residual leakage, so the device efficiency drops somewhat. Values of about 10 ⁵ -10 ⁸ Ω-cm are therefore more preferred. Values greater than ¹⁰⁹ will result in significant pressure drop across the thickness of the injection/buffer layer and should therefore be avoided. High Conductivity Third Layer(114)

The material for the third layer 114 is to be selected to match the energy level of the photoactive layer 102, or to improve the hole injection/transport capability of the multilayer anode 104, or to improve the interface between the multilayer anode 104 and the photoactive layer 102. interface performance.

The hole-injecting electrode This third component is a thin layer of highly conductive organic polymer with a resistance lower than that of the material of the second layer 112 and higher than that of the first layer 110 . A typical conductive organic polymer includes pure PANI in highly conductive form, polypyrrole, preferably polythiophene, such as PEDT, and any other material described in the previous section with respect to the second layer 112 .

The bulk conductivity of the material forming layer (114) should be from about 5 times to about ¹⁰⁶ times the bulk conductivity of the second layer (112). Likewise, the volume resistivity should be ^5-10 times lower. Where multilayer anode 104 is required to be transparent and the layer comprises PEDT, the third layer is typically very thin, often so thin that it hardly forms a complete continuous layer. The thickness should be in the range of about 5 Å to about 500 Å, generally preferably 10 Å to 50 Å.

The addition of a high conductivity third layer (114) on top of the second layer results in a multilayer structure with higher conductance than that observed with the second layer alone. The ratio of the conductance of the bilayer (112 and 114) structure to the conductance of the second layer 112 alone should be in the range of 1.25-20, preferably 1.5-15, especially preferably 2-10. Cathode(106)

Materials suitable for use as cathode material are any metal or non-metal having a lower work function than the first electrical contact layer (in this case, the anode). The material for the cathode layer 106 (in this case the second electrical contact layer) may be selected from group 1 alkali metals (eg Li, Cs); group 2 alkaline earth metals - typically calcium, barium, strontium; 12 metals; rare earth metals—typically yttrium, lanthanides, and actinides. Aluminum, indium and copper, silver, combinations thereof and combinations with calcium and/or barium, Li, magnesium, LiF, etc. can also be used. Alloys of low work function metals such as magnesium in silver and lithium in aluminum are also useful.

The thickness of the electron-injecting cathode layer ranges from less than 15 Å to as much as 5,000 Å thick. Cathode layer 106 can be patterned to give a pixelated array, or it can be continuous and overlap a layer of body conductor such as silver, copper or preferably aluminum which is itself patterned.

The cathode layer may also include a second layer of a second metal added to give mechanical strength and durability. Substrate(108)

In most embodiments, the diodes are fabricated on a substrate. In general, the substrate should be non-conductive. In light transmissive embodiments, it is transparent. The substrate can be a rigid material such as rigid plastics including rigid acrylics, polycarbonates, etc., rigid inorganic oxides such as glass, quartz, sapphire, etc. It may also be a flexible transparent organic polymer such as polyester - eg polyethylene terephthalate, flexible polycarbonate, polymethyl methacrylate, polystyrene, etc.

The thickness of the substrate is not too critical. Contact pads (80, 82)

Any contact pads 80, 82 suitable for connecting the electrodes of device 100 to a power source (not shown) may be used, including, for example, conductive metals such as gold (Au), silver (Ag), nickel (Ni), copper ( Cu) or aluminum (Al).

Preferably the height (not shown) of the contact pads 80, 82 exceeds the thickness of the high work function electrode line 110, which is below the total thickness of the layers.

Layers 102, 110 and 112 are preferably dimensioned such that contact pad 80 is located on a portion of the substrate not covered by 102, 112 and 114. In addition, the dimensions of the layers 106, 102, 110 and 112 are such that there is at least one layer 102, 112 interposed between the electrodes 106, 110 over the entire length and width of the electrode line 106 and the electrode line 110, and electrical connections can be made on the electrodes. 106 and contact pad 80 . other optional layers

Between the photoactive layer 102 and the cathode 106 there may be an optional layer comprising an electron injection/transport material. This optional layer can simultaneously facilitate electron injection/transport and act as a buffer or constraining layer to prevent quenching reactions at layer interfaces. Preferably this layer promotes electron mobility and reduces quenching reactions. Examples of electron-transporting materials for optional layer 140 include metal-chelating oxidation-type compounds such as tris(8-hydroxyquinate)aluminum (Alq ₃ ); phenanthroline-based compounds such as 2,9-bis Methyl-4,7-diphenyl-1,10-phenanthroline (DDPA) or 4,7-diphenyl-1,10-phenanthroline (DPA), and pyrrole compounds such as 2-(4- Diphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) and 3-(4-diphenyl)-4-phenyl-5-(4- tert-butylphenyl)-1,2,4-triazole (TAZ), polymers containing DIPA, DPA, PBD and TAZ moieties and blends thereof; polymer copolymers containing DDPA, DPA, PBD and TAZ mixture.

Some or all of the anode layers 110, 112, 114, photoactive layer 102, and cathode layer 106 may be surface treated to improve carrier transport efficiency. The choice of material for each element layer is preferably determined by balancing the goal of providing a high efficiency device. Manufacturing Technology

The various elements of the device of the present invention can be fabricated by any technique well known in the art, such as solution casting, screen printing, web coating, inkjet printing, sputtering, vapor coating, precursor polymer processing, melt processing, etc., or any combination thereof.

In the most common method, diodes are fabricated by sequentially depositing layers on a substrate. In a typical manufacturing method, the conductive first layer 110 of the composite electrode 104 is first applied. The method of depositing this layer is typically vacuum sputtering (RF or Magnetron), electron beam evaporation, thermal vapor deposition, chemical evaporation or similar methods commonly used to form inorganic layers.

Next, a low-conductivity second layer 112 is laid. The layer is often conveniently deposited from solution by spin casting or similar techniques. In the preferred case where the layer is formed from a water soluble or water dispersible material, water is generally used as the spin casting medium. Where non-aqueous solvents are required, toluene, xylene, styrene, aniline, decahydronaphthalene, chloroform, methylene chloride, chlorobenzene, and morpholine are used. This layer can be heat treated as described in commonly filed US Provisional Patent Application 60/212,934.

Then, a higher conductivity layer 114 is deposited. This step is also typically formed from solution, with the solvent selected as described in references for layer 112 deposition.

Then, a photoactive layer 102 of conjugated polymer is deposited. Conjugated polymers can be deposited or cast directly from solution. The solvent used is one that dissolves the polymer without interfering with its subsequent deposition.

Usually organic solvents are used. Such solvents may include halogenated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride, aromatic hydrocarbons such as xylene, benzene, toluene, other hydrocarbons such as decahydronaphthalene, and the like. Mixed solvents can also be used. Polar solvents such as water, acetone, acids, etc. are also suitable. These are merely representative examples, and the solvent can be selected from a wide range of materials satisfying the above criteria.

When depositing various polymers on the substrate, the solution should be relatively dilute, for example, the concentration is 0.1-20% by weight, especially 0.2-5% by weight. The film thickness is generally 500 Å-4000 Å, especially 1000 Å-2000 Å.

Finally, low work function electron-injection contacts are added. This contacting is generally by vacuum evaporation on the surface of the active polymer layer.

The above steps can be changed or even reversed, if desired to "invert the diode".

It should be understood that the structures described above and their methods of fabrication may be modified to include other layers that impart physical strength and protection, to change the color of emitted light or the sensitivity of the diodes, and the like. It should further be understood that the present invention is also applicable to organic electronic devices, including multilayer anodes of the present invention that do not contain a photoactive layer, such as transistors, capacitors, resistors, chemical resistance sensors (gas/vapor sensitive electronic probes, chemical and biological sensors), write sensors and electrochromic sensors (smart windows).

The present invention will be further described by the following examples, which are given for the purpose of illustration of the invention and are not intended to limit the scope of the invention.

Example 1

PANI(ES) was prepared according to the following reference (Y. Cao et al., Polymer, 30(1989) 2307). The emeraldine salt (ES) form is evidenced by a typical green color. Poly(2-propenylamino-2-methyl-1-propanesulfonic acid (PAAMPSA) (Aldrich) was used to replace HCl in the reference. First, in 30.5 g (0.022 mol) of 15% aqueous solution of PAAMPSA (Aldrich) Add 170ml of water to make it diluted to 2.3%. While stirring, add 2.2g (0.022M) aniline in the PAAMPSA solution. Then in vigorous stirring, slowly add 2.01g (0.0088M) in the aniline/PAAMPSA solution Ammonium persulfate in 10 ml of water. The reaction mixture was stirred at room temperature for 24 hours. To precipitate out the product PANI(ES), 1000 ml of acetone was added to the reaction mixture. Most of the acetone/water was decanted and the PANI(ES) precipitate was filtered The resulting gummy product was washed several times with acetone and then dried at 40°C under dynamic vacuum for 24 hours.

This example illustrates the direct synthesis of PANI(ES).

Example 2

4g of PANI(ES) powder prepared in Example 1 was mixed with 400g of deionized water in a plastic bottle. The mixture was rotated at room temperature for 48 hours. The solution/dispersion was then filtered through a 1 μm polypropylene funnel. PANI(ES) aqueous solutions with different concentrations were prepared by changing the amount of PANI(ES) mixed in water as a routine procedure.

This example shows that PANI(ES) can be dissolved/dispersed in water and then filtered through a 1 μm funnel.

Example 3

Dilute polyethylenedioxythiophene PEDT (Baytron P. special grade, purchased from Bayer) solution with an equal amount of deionized water. The solution was stirred overnight at room temperature. The PEDT content in the solution was 0.8%. PEDT solutions with PEDT contents of 0.4, 0.2 and 0.16%, respectively, were also prepared. All of these solutions were able to filter through 0.231 μm funnels.

Example 4

30 g of PANI (ES) prepared in Example 2, 7 g of deionized water and 0.6 g of polyarylamide (PAM) (M.W. 5,000,000-6,000,000, Polysciences) were stirred and mixed at room temperature for 4-5 days. The weight ratio of PANI(ES) to PAM in the blend solution is 1:2. Blend solutions with weight ratios of PANI(ES) to PAM of 1:1, 1:1.5, 1:2.5, 1:3, 1:4, 1:5, 1:6 and 1:9 were also prepared .

Example 5

Prepare glass substrates with patterned ITO electrodes. Using the PANI, PEDT and PANI blend solutions prepared in Examples 2, 3 and 4, the layers were spin-cast on the surface of the patterned substrate, and then baked in a vacuum oven at 90° C. for 0.5 hour. The films were then oven-conditioned at 200°C for 30 minutes. The resistance between the ITO electrodes was measured with a high-resistance electrometer. Film thickness was measured with a Dec-Tac Surface Profiler (Alpha-Step 500 Surface Profiler, Tencor Instrument). Table 1 compares the conductivity and thickness of PANI(ES), PANI(ES)-PAM blend and PEDT membranes. As can be seen from the table, the conductivities of PANI(ES) and PEDT are 10 ^-4 and 10 ^-3 S/cm, respectively. Both values are too high for pixelated displays. High temperature processed PANI(ES)-PAM blends have the ideal conductivity and thickness of these materials for pixelated displays.

This embodiment illustrates that the PANI (ES) blend that has been processed at high temperature has ideal conductivity and thickness suitable for pixelated displays; is limited sufficiently low.

Table 1: Bulk conductivity of PANI(ES), PANI(ES)-PAM blends and PEDT

Blend Baking Conditions Thickness () Conductivity (S/cm)

PANi ---------- 426 5.1×10 ^-4

PEDT ---------- 1221 1.8×10 ^-3

PANi-PAM(1:2) 200℃/30min 2195 7.4×10 ^-7

Example 6

With soluble poly(1,4-phenylene vinylene) blends (C-PPV) (H.Becker, H.Spreitzer, W.Kreduer, E.Kluge, H.Schenk, ID Parker and Y.Cao, AdV.Mater.12,42(2000) manufacture light-emitting diode as active semiconducting light-emitting polymer; The thickness of C-PPV film is 700-900 Å.C-PPV emits yellow-green light, and luminescence peak is at～560nm.Use indium/ Tin oxide is used as the anode contact layer. Then with embodiment 2, the solution coating PANI, PEDT or PANI-PAM blend layer in the preparation in 3 and 4.These layers form by spin casting on patterned substrate surface.These The layer is baked in a vacuum oven at 90°C for 30 minutes, and then treated in an oven at 200°C for 30 minutes. Add the active layer and a metal cathode. The structure of the device is ITO/polyaniline blend/C-PPV/ Metal. Devices were fabricated using ITO on glass (Applied ITO/glass) and ITO on polyethylene terephthalate PET plastic as a substrate (ITO/PET from Courtauld); Aniline blend double layer is the anode and the hole-injection contact. The device is fabricated with a layer of Ca or Ba as the cathode. On the surface of the C-PPV layer at a pressure lower than 1× ^10-6 Torr by vacuum vapor deposition Fabricate the metal cathode film to form an active layer with an area of 3 ^cm . Deposition is monitored with an STM-100 thickness/rate meter (Sycon Instruments). 2,000-5,000 Å of aluminum is deposited on a 15 Å barium layer. For each device, the measured Current-voltage curves, light-voltage curves, and quantum efficiencies. The operating voltages and efficiencies measured for devices with different blend layers are summarized in Table 2. As can be seen from these data, the lowest operating voltage and highest light output achieved by devices containing PEDT layers.

This example demonstrates that the best performing polymer LEDs can be made with PEDT as the hole injection (buffer) layer.

Table 2 Properties of devices made of PANI(ES), PANI(ES)-PAM blends and PEDT

Blend Baking Condition Device Performance at 8.3mA/cm ²

V cd/A Lm/W

PANi --------- 4.7 7.4 4.9

PEDT --------- 4.5 7.7 5.2

PANi-PAM(1∶2) 200℃/30min 6.6 7.2 3.6

Example 7

The device produced in Example 6 was encapsulated with a cover glass sandwiched between UV-cured epoxy. A constant current of 3.3 mA/cm ² was passed through the packaged device at a temperature of 70° C. in an oven. The total current through the device was 10 mA and the luminous intensity was 200 cd/cm ² . Table 3 and Figure 3 illustrate the light output and voltage rise during operation at 70°C. Light outputs 300-1, 302-1, and 304-1 of devices 300, 302, and 304, respectively, are shown in dashed lines in FIG. Voltage outputs 300-2, 302-2, and 304-2 of devices 300, 302, and 304, respectively, are shown in solid lines in FIG.

In contrast to the degradation of devices with PANI(ES) and PANI(ES)-PAM blends as anodes under stress at 70 °C within 160–190 h, the half-life of devices with PEDT layers reached 300 h, accompanied by a Non-low boost (4.3mV/hour). Its lifetime is almost 2 times longer than the device with PANI(ES)-PAM blend. However, the resistance of the PEDT layer alone is not high enough to avoid leakage between pixels, so it is not suitable for pixelated displays. From the Ahrennius curves of luminance decay and voltage rise data collected at 50°C, 70°C, and 85°C, a temperature acceleration factor of about 25 was estimated at 70°C. The extrapolated stress lifetime at room temperature was thus determined to be approximately 7,500 hours for a device with a PEDT layer.

This example illustrates that the longest lifetime can be obtained from polymer LEDs made from PEDT layers. However, the resistance of these layers is not high enough to avoid leakage between pixels. Table 3: Stress lifetime of LED devices fabricated with PANI(ES), PANI(ES)-PAM blends, and PEDT

Fig.3 Stress life of blends baked at 70℃3.3mA/ ^cm2

Reference No

mV/h cd/m ² * t _1/2 (h)

300 PANi ------- 7.4 185 186

-

302 PEDT ------- 4.3 185 300

-

304 PANi-PAM(1∶2) 200℃/30 11.3 171 168

min

^* Initial brightness

Example 8

Repeat the resistance measurement in Example 5, but the PANI((ES) layer is cast from the blend solution prepared in Example 4 with a rotating speed of 1400rpm. The weight of PANI(ES) and PAM in the blend solution The ratio is 1: 2. The film was baked at 90° C. for 0.5 hour in the vacuum oven and then baked at 200° C. for 30 minutes in the oven. The PEDT film was spin casted on the PANI blend from the solution made in Example 3 The surface of the layer. The thickness of the PEDT layer is 970 -～10 . The resistance between the ITO electrodes is measured with a high-resistance electrometer. The film thickness is with the Dec-Tac surface profiling instrument (profiler) (Alpha-Step500 surface profiling instrument, Tencor Instrument) measurement. Table 4 provides the surface resistance of the different PANI (ES)-blend/PEDT bilayer film of PEDT thickness.As seen from table, by regulating the thickness of PEDT layer, PANI (ES)-blend The surface resistance of the /PED double layer can be controlled in a wide range of 10 ⁷ -10 ⁹ Ω/sq. With the thickness of PEDT reduced below 50 Å, the conductivity of the double layer is lower than 10 ⁸ Ω/sq, which Ideal for pixel displays.

This example demonstrates that PANI(ES)-blend/PEDT bilayer membranes can be made with conductivity below 10 ⁸ Ω/sq.

Table 4: Surface resistance of PANI(ES)-PAM/PEDT bilayers with different thicknesses of PEDT

PEDT Solution Rotation Speed PEDT Thickness Double Layer Thickness Surface Resistance

Concentration (%) (rpm) () () Ω/sq

1.6 800 970 2768 5.8×10 ⁷

0.8 3000 192 1788 4.0×10 ⁸

0.8 6000 90 1962 5.8×10 ⁸

0.4 6000 ~ 50 2694 1.4×10 ⁹

0.2 3000 ～40 2025 5.3×10 ⁹

0.2 6000 ~ 20 1640 6.1×10 ⁹

0.16 4000-10 2045 5.8×10 ⁹

Example 9

The device measurements outlined in Example 6 were repeated, but with the PANI(ES)-blend/PEDT bilayer prepared in Example 8 instead of the PANI blend. Table 5 presents the device performance of LEDs fabricated from blended films with different bilayers. Devices made with PANI blend/PEDT bilayer have the same operating voltage and luminous efficiency as devices made with PEDT layer.

This example demonstrates that a PANI blend/PEDT bilayer can be used to make polymer LEDs with the same low operating voltage and high efficiency as devices made with PEDT layers.

Table 5: Devices fabricated with PANI(ES)-PAM/PEDT bilayers with different thicknesses of PEDT

performance

PEDT solution Rotation speed PEDT thickness Device performance at 8.3mA/cm ²

Concentration (%) (rpm) () V V cd/A Lm/W

1.6 800 970 5.3 6.9 4.1

0.8 3000 192 4.3 7.2 5.2

0.8 6000 90 4.2 7.6 5.6

0.4 6000 ～50 4.2 7.6 8.2

0.2 3000 ～40 4.9 8.0 5.1

0.2 6000 ～20 4.7 8.3 5.5

0.16 4000 ～10 5.0 8.1 5.1

Example 10

The stress measurements outlined in Example 7 were repeated, but replacing the PANI-blend layer with the PANI-blend/PEDT bilayer prepared in Example 8 (incorporated into device 300 in Table 3). Table 6 and Figure 4 show the stress lifetime of devices made with PANI blend/PEDT bilayers. In FIG. 4, the light outputs 302-1, 304-1, 402-1, 404-1, and 406 of devices 302 and 304 shown in Table 3 and devices 402, 404, and 406 shown in Table 6 are given, respectively. -1, as indicated by the dashed line. For devices 302 and 304 shown in Table 3 and devices 402, 404 and 406 shown in Table 6, their voltage outputs 302-2, 304-2, 402-2, 404-2 are given in solid lines, respectively and 406-2.

As can be seen from the data in the table, for bilayer devices with PEDT layer thicknesses of -10 Å-20 Å, the rate of voltage rise is slightly lower than for devices made from PEDT. The half-life of the bilayer device is even slightly longer than that of the PEDT device.

This example illustrates that a PANI blend/PEDT bilayer can combine the high electrical resistance of a PANI blend with the long stress life of PEDT in one device. Table 6: Stress lifetime of LED devices fabricated with PANI(ES)-PAM/PEDT bilayers with different PEDT thicknesses

Fig.4 PEDT solution Rotation speed PEDT thickness at 70℃ and 8.3mA/ ^cm2

Stress life of

Reference No. Concentration (%) (rpm) () MV/h cd/m ² * t _1/2 (h)

1.6 800 970 9.2 194 221

0.8 3000 192 5.8 144 300

402 0.8 6000 90 3.8 189 319

404 0.4 6000 ～50 3.4 171 350

0.2 3000 ～40 4.7 189 303

406 0.2 6000 ～20 4.2 190 328

0.16 4000 ～10 3.8 190 330

^* Initial brightness

Example 11

The resistance measurements of Example 5 were repeated, but with the blend solution prepared in Example 4 the PANI(ES) layer was spin cast. In the blend solution, the weight ratio of PANI(ES) to PAM was 1:1.5, 1:2, 1:3, 1:4, 1:5 and 1:6. The film was baked in a vacuum oven at 90° C. for 0.5 hour, and then baked in an oven at 200° C. for 30 minutes. A PEDT film was spin-cast from the solution prepared in Example 3 on the surface of the PANI blend layer. The concentration of the PEDT solution was 0.16%, and the rotation speed was 4000 rpm. The thickness of the PEDT layer is ~10 Å. The resistance between the ITO electrodes was measured with a high-resistance electrometer. The film thickness was measured with a Dec-Tac surface profiler (Alpha-Step 500 surface profiler, Tencor Instrument). Table 7 shows the surface resistance of PANI blend/PEDT bilayer films with different ratios of PANI(ES) and PAM. As can be seen from the table, the surface resistance of the PANI blend/PEDT bilayer can be controlled within a wide range of 10 ⁸ -10 ¹⁵ Ω/sq by adjusting the weight ratio of the PANI(ES)-PAM layer.

This example shows that the PANI blend/PEDT bilayer film can be made with a conductivity lower than 10 ⁸ Ω/sq or even lower than 10 ¹³ Ω/sq. Table 7 Surface resistance of PANI(ES)-PAM/PEDT bilayers with different PANI(ES)-PAM blends

PANI Blend Composition Double Layer Thickness Surface Resistance

(w:w) () (Ω/sq)

PANI-PAM 1:1.5 1822 6.6×10 ⁸

PANI-PAM 1:2 2078 5.7×10 ⁹

PANI-PAM 1:3 2252 2.1×10 ¹³

PANI-PAM 1:4 1621 1.1×10 ¹⁵

PANI-PAM 1:5 1734 9.0×10 ¹⁴

PANI-PAM 1:6 2422 9.6×10 ¹⁴

Example 12

The device measurements outlined in Example 6 were repeated, but replacing the PANI blend layer with a PANI blend/PEDT bilayer. Table 8 presents the device performance of LEDs made from blended films with different bilayers. When the ratio of PANI to PAM is greater than 1:4, the devices made with PANI blend/PEDT bilayer exhibit the same operating voltage and luminous efficiency as those made with PEDT layer alone. Lower ratios of PANI(ES) to PAM degrade device performance.

This example demonstrates that a PANI blend/PEDT bilayer can be used to make polymer LEDs with the same operating voltage and high efficiency as devices made with the PEDT layer alone. Table 8 Properties of devices made of PANI(ES)-PAM/PEDT bilayers with different PANI(ES)-PAM blends

PANI blend Composition Bilayer thickness Device performance at 8.3mA/ ^cm2

(w:w) () V V cd/A Lm/W

PANI-PAM 1:1.5 1822 6.0 6.4 3.4

PANI-PAM 1:2 2078 5.0 8.1 5.1

PANI-PAM 1:3 2252 5.8 7.9 4.3

PANI-PAM 1:4 1621 5.8 8.8 4.6

PANI-PAM 1:5 2422 8.0 8.7 3.1

PANI-PAM 1:6 2078 8.3 8.2 3.0

Example 13

The stress measurements outlined in Example 7 were repeated, but replacing the PANI(ES)-blend layer with a PANI blend/PEDT bilayer. Table 9 and Figure 5 show the stress lifetime of devices made of PANI(ES) blend/PEDT bilayer at 80°C. Luminous intensities 500-1, 502-1, 504-1, and 506-1 of devices 500, 502, 504, and 506 are shown in dashed lines in FIG. 3, respectively. Voltage outputs 500-2, 502-2, 504-2, and 506-2 of devices 500, 502, 504, and 506 are shown in solid lines in FIG. 5, respectively. When the ratio of PANI to PAM is greater than 1:4, the voltage rise rate of the bilayer device is lower than that of the device made of PEDT. The half-life of the bilayer device at 80 °C is even longer than that of the PEDT device.

This example illustrates that a PANI(ES) blend/PEDT bilayer can combine the high electrical resistance of a PANI blend with the long stress lifetime of PEDT in one device. Table 9: Stress lifetime of LED devices made with PANI(ES)-PAM/PEDT bilayers with different PANI(ES)-PAM blends

Composition of PANI in Fig. 5 Bilayer thickness at 70°C and 3.3mA/ ^cm2

Reference No. Blends () Stress Life

(w:w) mV/h cd/m ² * t _1/2 (h)

500 PEDT ------ --- ------ 19.6 217 80

PANI-PAM 1:1.5 1822 19.8 198 108

502 PANI-PAM 1:2 2078 15.7 210 123

                                                                                                                                                     

504 PANI-PAM 1:4 1621 19.5 229 81

506 PANI-PAM 1:5 2422 67.2 232 61

                                                                                              

^* Initial brightness

Claims (10)

1. A multilayer electrode (104) comprising a first layer (110) having a first layer conductivity, a second layer (112) in contact with the first layer, the second layer comprising a conductive organic material having a second layer conductivity, and a third layer (114) in contact with the second layer, the third layer comprising a conductive organic material having a third layer conductivity, the third layer conductivity being greater than the second layer conductivity and less than the first layer conductivity.

2. A pixelated display comprising the multi-layer electrode of claim 1.

3. An electronic device comprising a photoactive layer (102) between a cathode (106) and an anode, wherein the anode is the multilayer electrode of claim 1.

4. The device of claim 3, wherein the cathode comprises a first cathode layer of a low work function material and a second layer of an electron transport/injection material interposed between the photoactive layer and the first cathode layer, the first anode layer having an anode work function and the low work function material having a cathode work function such that the anode work function is higher than the cathode work function.

5. The multilayer electrode of claim 1 and/or the display of claim 2 and/or the device of any one or both of claims 3 to 4, wherein the second layer in the multilayer electrode comprises a blend of a conjugated conductive organic polymer and a non-conductive polymer.

6. The multi-layer electrode of claim 1 and/or the display of claim 2 and/or the device of any one or both of claims 3 to 4, wherein a second layer in the multi-layer electrode comprises a blend of PANI and a non-conductive polymer.

7. The multilayer electrode of claim 1 and/or the display of claim 2 and/or the device of any one or both of claims 3 to 4, wherein the bulk conductivity of the second layer in the multilayer electrode is 10^-4S/cm-10^-11S/cm and wherein the bulk conductivity of the third layer is from about 5 times to about 10 times the conductivity of the second layer⁶And (4) doubling.

8. A multilayer electrode according to claim 1 and/or a display according to claim 2 and/or a device according to any one or both of claims 3 to 4, wherein the conductance of the second layer in combination with the third layer in the multilayer electrode is from 1.25 times to about 20 times the conductivity of the second layer itself.

9. The multilayer electrode of claim 1 and/or the display of claim 2 and/or the device of any one or both of claims 3-4, wherein the second layer of the multilayer electrode has a thickness of from about 500  to about 5000 .

10. The multilayer electrode of claim 1 and/or the display of claim 2 and/or the device of any one or both of claims 3-4, wherein the third layer of the multilayer electrode has a thickness of from about 2  to about 400 .

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